Bad aquastat?
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Bad aquastat?
I have an L8148A aquastat, on our Weil-McLein (both about 28 years old). The system was drained down this summer when I had to replace a circulator pump. It is refilled, and all radiators bled. When the thermostat calls for heat now, I noticed that the pipes/radiators don't get very hot. Temp/pressure gauge on the system said it was about 18 lbs at about 120 degrees. I opened the aquastat and dialed it up from about 140 to now indicate 200. When it runs now, it reports about 140 degrees. Is it possible that the boiler could have air in it? Should I replace the aquastat? I've seen on other posts the suggestion to replace the L8148 with an L7224U1002. Does this make sense in this application? One other issue that might be relevant. I notice that the aquastat seems to make a low level hum almost constantly. The transformer? Is this normal? Sorry for lots of questions, and I know that in responding you'll likely need more info. Thanks in advance!
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With a multimeter, see if contacts on the aquastat are closing when the boiler temp is below the setpoint and there is a heat call. It sounds like they are not.
#3
It is refilled,
dialed it up from about 140 to now indicate 200
Is it possible that the boiler could have air in it?
It's also possible that the thermometer on the boiler is defective.
replace the L8148 with an L7224U1002. Does this make sense in this application?
Patriot Supply - L7224U1002
Patriot Supply - L8148A1017
Diagnose the problem fully before changing parts.
the aquastat seems to make a low level hum almost constantly. The transformer? Is this normal?
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I'm reasonably confident that it is full, but not completely (confident), as I read on another thread about the probe well possibly not being immersed in water. But, would I be likely to have successfully bled the radiators on first and second floor with water still in the boiler? Is there a way to bleed the boiler itself?
140 is low for a high limit setting, and 200 is probably needlessly high. I would set it at 180.
Yes it's possible...
It's also possible that the thermometer on the boiler is defective.
It's also possible that the thermometer on the boiler is defective.
Yes probably the transformer. Normal? I guess it depends on how loud it actually is. If you have to strain to hear it, yes, I would call that normal. If it's so loud that you can hear it upstairs with the TV on, no, that's not normal. I would say most likely it's a 'non-issue' based on your description.
Gilmorrie, I tried to test with the multimeter, a tool with which I am not terribly adept. If I was using the correct contacts (outside of the adjuster dial), and if I was using the correct scale on the multimeter, the reading was .8 when the thermostat was not calling for heat, and .4 when it was.
Last edited by NJT; 11-28-11 at 06:42 PM. Reason: fixed quotes
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follow-up thought to question of boiler being full or not
I spent a lot of time in bed thinking about this last night. If the boiler somehow had enough air in it to have the probe's well not immersed, wouldn't my problem be the flame running too long and water overheating, since the aquastat would not know that it was reaching high limit temp? Just a thought.
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Thanks Saves. I'll do this later today. I've been reluctant to do it as last time I used it, a few years ago, I had a hard time getting it to stop dribbling completely. I suppose I should just go ahead and replace it. Maybe this time. It is warm out now, so a good time to try it.
#13
If the boiler somehow had enough air in it to have the probe's well not immersed, wouldn't my problem be the flame running too long and water overheating, since the aquastat would not know that it was reaching high limit temp?
reluctant to do it as last time I used it, a few years ago, I had a hard time getting it to stop dribbling completely. I suppose I should just go ahead and replace it.
If the relief valve is over 5 years old, just replace it... next time...
One 'trick' that sometimes works for a dribbling valve, and sometimes not... lift the handle all the way up and release and let it 'snap' shut.
If I touch the edge of the transformer I can make the hum stop.
Is this sounding more like the aquastat?
Are you sure that there are no other high limit controls, etc, wired in series with the limit switch?
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NJ Trooper, Thanks for your responses. I'm not real experienced with this arena (as you can tell), but you're confirming my logic. It is a pretty simple looking installation and I don't see any other things that look like they could be high limit controls. I think I'll bite the bullet and order a new aquastat and go ahead and swap it out. I'll let you know how this works.
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I just finished installing and testing a new aquastat and all seems to be right with the world, well, almost all. The system runs fine and the water now got up to about 175 degrees with the adjuster set at 180. the thermostat stopped calling for heat before it got all the way to 180, as it is not too cold outside. Thanks very much for your advice and giving me the confidence to go ahead with this. By the way, I ordered the part from PexUniverse.com and they got it to me in just over 24 hours, on the cheapest shipping option. Great price and service - I'd recommend them.
One question: A relatively new (1 year old) circulator pump motor gets pretty hot during extended operation. To the point that I can't leave my hand on the motor housing. Is this normal? We used to run a B and G "little red pump" and I don't remember it getting nearly that hot.
Thanks again!!
One question: A relatively new (1 year old) circulator pump motor gets pretty hot during extended operation. To the point that I can't leave my hand on the motor housing. Is this normal? We used to run a B and G "little red pump" and I don't remember it getting nearly that hot.
Thanks again!!
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One question: A relatively new (1 year old) circulator pump motor gets pretty hot during extended operation. To the point that I can't leave my hand on the motor housing. Is this normal? We used to run a B and G "little red pump" and I don't remember it getting nearly that hot.
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gilmorrie,
The new pump is a Taco 007. I did not even consider that this was the water temp making the pump hot. Perhaps, but what I think I'm feeling is the motor section of the pump rather than the rotor section. It was running hot even before the new aquastat raised the water temp.
The new pump is a Taco 007. I did not even consider that this was the water temp making the pump hot. Perhaps, but what I think I'm feeling is the motor section of the pump rather than the rotor section. It was running hot even before the new aquastat raised the water temp.
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The Taco 007 is a canned motor pump. The rotor is immersed in the hot water being pumped, unlike your old B&G pump. The motor and the pump are all one "section," not separate. It has only one moving part - the rotor (cartridge), which includes the impeller and the motor. You could buy another cartridge - if, as I suspect, it makes no difference, you'll have a spare. Or, just stop worrying.